Coating of pipes.



lit

lit

; l l wt;

EDWIN '1. GBEENFIELD, F KIESHA, NEW YORK.

COATING 0F PlllPlfi mamas. no wing.

To all whom it may concern:

Be it known that I, EDWIN T. GREENFIELD, a citizen of the United States, and resident of Kiamesha, county of Sullivan, and State of New York, have invented new and useful Improvements in the Coating of Pipes, of which the following is a specification.

The invention relates to the coating of iron or steel pipes by immersing them or dipping them in a bath of molten zinc.

Frequently it i necessary to have the pipe coated on only one side with the zinc, for example,the outside portion of the pipe and in such case it is frequently desirable not to coat the inside of the pipe with the zinc for the reason that the zinc is at all times more or less expensive and for the further reason that frequently the pipe is provided with an enamel coating, especially where the pipe is to-be utilized as a conduit or duct for electric wiring and where an enamel coating is applied to the interior of the pipe a coating of zinc on the interior of the pipe will be The present invention depends or hinges upon the principle that molten zinc will not adhere to a metal which is clean. Tn performing the invention the pipe is first cleaned. This is accomplished by submerging the pipe in or subjecting it to the action of a pic le which comprises as a part thereof sulfuric acid, for example from four to six per cent'. scale and in fact cleans both the exterior and interior of the pipe. Thereafter the pipe is washed with clean water as bysubmergmg tlo the pipe in water and this washing removes all of the sulfuric cid and leaves the pipe practically clean. After this operation a flux in the form of a liquid comprising as a component part thereof muriatic acid is applied to the exterior portion only of the pipe. In other words, this flux is applied to only that portion of the pipe which it is desired to coat with the zinc. The interior of the pipe is left in the same clean condition that existed after the washing operation. The pipe when thus prepared is now ready for immersion or dipping in a bath of molten metal composed of or containing a'large per- Specifieation of Letters Patent.

This pickling removes any.

centage of zinc. The zinc is allowed to contact with all portions of the pipe both on the inside and the outside. The pipe is then withdrawn from the molten bath and any excess coating material on the outside of the pipe can be removed by any of the well known methods as for example, by wiping of the exterior portion of the pipe or by directing a knifeedge blast of air against the pipe. As the exterior portion of the pipe was coated with the fluxing material before the pipe was dipped into the molten bath a coating of the material which was in the bath will remain on the exterior of the pipe when the pipe i cold. After the pipe is removed from the molten bath the material on the inside thereof is allowed or caused to flow from the interior of the pipe in any suitable manner and none of the.

molten metal will adhere to the interior of the ipe for the reason as above expressed the interior of the pipe was clean at the time the pipe Was immersed or dipped in the liquid.

The result of the. operations above described is an iron or steel pipe which has a coating of zinc on the exterior but which is clean and has no coating of zinc on the interior even though the molten coating main such proportion that the coating applied to the pipe comprises zinc in substantial quantities would come within this invention.

The improvements herein set forth may be performed in various ways without departing from the spirit and scope of the invention.

at l claim is: 1. In the coating of an iron or steel pipe Patented Jan. 2%, TWL.

Application filed November 27, 1915. Serial No. 63,824.

the method which comprises cleaning the pipe on both the exterior a'ndinterior exposed metal portions thereof, applying a flux to one of said portions only, leaving the portion not to be coated exposed, immersing or dipping said pipe in a molten bath comprising zinc, removing the said pipe from the bath and allowing or causing the molten metal to flow from the portion of the pipe which was left clean and which'was not provided with a flux whereby the resulting article will be a pipe having a zinc coating upon only that portion to Which the flux was aplied. p 2. The method of coating an iron or steel pipe on the exterior portion thereof only which method comprises pickling said pipe on both the exterior and the interior, washing said pipe so that the exterior and interior portions thereof will be clean, applying a flux to the exterior portion only of the pipe, leaving exposed the interior portion of the pipe, immersing said pipe in a molten bath containing zinc, removing said pipe from the bath and allowing or causing the zinc to flow from the clean interior exposed metal portion of the pipe thus leaving the pipe with a coating on the exterior portion thereof only.

3. The method which comprises subjecting the exterior and interior of an iron or steel pipe to the pickling action of a bath containing sulfuric acid, washing said pipe in water so that the pickled interior and exterior portions thereof will be clean, applying a flux containing muriatic acid to the exterior portion of the pipe, leaving the interior. portion of the pipe exposed and in the condition existing after washing, dipping said pipe in a bath of molten metal containing zinc, removing said pipe from said bath and removing any excess molten metal on the exterior of the pipe, allowing the molten metal on the interior of the pipe to'flow therefrom.

4. In the treating of a non-coated iron or steel pipe so as to provide a zinc coatin on only the exterior thereof the method W ich comprises applying a solution containing sulfuric acid to both the exterior and in terior of the pipe, thereafter washing the pipe with water so that the interior thereof will be clean, muriatic acid on the exterlor thereof and leaving the interior of the pipe exposed, placing or immersing the pipe having the clean exposed interior and the flux coated exterior in a bath containing molten zinc, removing the pipe from said molten bath and allowing or causing the molten metal to flow from the exposed metal on the interior of the pipe whereby the resulting product will bean iron or steel pipe havmg a zinc coated exterior only.

applying a flux containing 5. The method of treating pipe which method comprises cleaning the exposed metal on both the exterior and interior thereof by means of a suitable pickle, washing the pipe so that the, exposed metal on the interior thereof will be clean and free from the pickle, applying a suitable flux to the exterior of the pipe, leaving the clean interior exposed, then passing the pipe into a bath of molten metal containing zinc and after the pipe has been removed from the molten metal allowing or causing the molten metal to flow from said exposed metal on the clean exposed interior of the pipe and removing any excess metal from the exterior of the pipe thus leaving the pipe wiph a coating of zinc on the exterior thereof on y.

6. The manufacture of a pipe having a coated surface and an exposed cleaned metal or non-coated surface by the method which comprises cleaning a pipe on both the exterior and the interior portions thereof, applying a flux to only the surface to be coated, leaving the surface which is not to be coated exposed, immersing or dipping said pipe in a molten bath comprising zlnc, removing said pipe from the bath and allowing or causing the molten metal to flow from the portion of the pipe which was left clean and which was not provided with a flux whereby the resulting article will be a pipe having a zinc coating upon only that portion to which the flux was applied.

7. The manufacture of a pipe so that it :will have a coated exterior and a cleaned non-coated exposed metal interior by the method which comprises pickling a pipe on both the exterior and the interior, washing the pipe thus pickled so that the exterior and interior portions thereof will be cleaned, applying a flux to the exterior portion only of the pipe, leaving exposed the interior which is not to be coated, immersing said pipe in a molten bath containing zinc, removing said pipe from the bath and-allowing or causing the zinc to flow from the cleaned interior exposed metal portion of the pipe thus leaving the pipe with a coating on the exterior portion thereof only.

8. The manufacture of a pipe sotthat it will have a coated exterior and an exposed metal interior by the method which comprises taking an iron or steel pipe subjecting the exterior and interior of said iron or steel pipe to the pickling action of a bath containing sulfuric acid, Washing said pickled pipe with water so that the pickled interior and pickled exterior portions thereof will be cleaned, applying a flux containing muriatic acid to the exterior portion of the pipe leaving the interior portion of the pipe exposed and in the condition existing after washing, dipping said pipe in a bath an iron or steel WW I W ofmolte n metal containing zinc, removimg "This specification si ed @1101 witmssdd said pipe from said bath, removing any this 26th day of Novena (213A. 111915.. excess molten metal on the exterior of the EDWKNT. GREENFIELD. pipe, and allowing the molten metal on the Signed in the presence oi 5 interior of the pipe to flow-from the Washed Gr. MOG'RANN,

pickled interior surface. 7 EDWIN PACKARD. 

